1. Field of the Invention
The present invention relates to the device of monitoring UV, and in particular relates to the UV monitoring device integrated in the portable display device.
2. Description of the Related Art
The need for monitoring of the sun's UV radiation dose is well understood, in particular amongst those who sunbathe and who wish to minimize the risk of exceeding a healthy dose. Daily weather forecasts offer a crude UV index which gives a rough indication as to the likely ‘burn time’ of the average person in the sun, but since local exposure conditions are affected by effects such as cloud cover, this can only offer a very crude indication of the total dose. The monitoring of UV from sun exposure therefore requires a personal solution.
The spectral content of the sun's UV radiation is categorized by wavelength into UVA (400 nm to 320 nm), UVB (320 nm to 290 nm) and UVC (290 nm to 100 nm), based on its effect on the human skin. Whilst all wavelengths cause local heating, it is UVA that is responsible for skin ageing and UVB that is responsible for skin burning and non-melanoma skin cancer. UVC is largely filtered out by the earth's atmosphere. At low dose levels the damage to skin caused by UV is generally accepted to integrate over time, therefore the integrated dose must be measured over a period of sun exposure, and will account for time variations in the intensity due to for example cloud cover.
Existing solutions to monitoring the UV dose are available in the form of disposable patches which change color after a predetermined UV dose, bespoke monitoring units that are integrated into watches and wall-mounted weather station units that are used to monitor the UV dose in the user's back garden. However these all suffer from drawbacks. The disposable patches, whilst worn and therefore give a direct monitor of the dose, cannot be re-used and are therefore wasteful and require the user to carry an adequate supply. The sensors that are integrated into for example watches, require a dedicated photodetector and the corresponding filters in order to monitor the UV. The use of a dedicated photodetector in the sensing product increases cost and manufacturing complexity, and in some solutions requires a costly SiC or TiO2 detector. The larger weather station wall-mounted units suffer from being bulky and are therefore non-portable.
Accordingly, a novel UV monitoring device without largely changing the existing processes is called for simplifying the manufacture and reducing the cost. In addition, this device should overcome the limitations of the related art, being incompatible with a portable unit, and eliminating the need for an expensive filter that is typically used in existing systems.